It’s finally official — Marvel has confirmed that Vin Diesel will voice the sentient tree Groot in the studio’s 2014 release “Guardians of the Galaxy.”

“Guardians of the Galaxy,” directed by James Gunn and based on the Marvel comic series of the same name, follows roguish antihero Peter Quill, a.k.a. Star-Lord (Chris Pratt), and his squad of aliens tasked with teaming up to battle cosmic threats. Included in the group is the furry, fan-favorite character Rocket Raccoon, to be voiced by Bradley Cooper.

It’s an oddball idea, and the footage screened this year at San Diego’s Comic-Con International suggested the film adaptation will embrace its humorous elements with snark and irreverence.

Diesel had spoken publicly about the role for some time. In October, he released on his Facebook page a video in which he walked around on stilts and talked about “Guardians of the Galaxy.” Before that, the actor had posted a picture of the character on his Facebook page, and he openly discussed the role with Hero Complex back in August.

The news follows Thursday’s confirmation that Paul Rudd will star as scientist Hank Pym in Marvel’s upcoming Edgar Wright film, “Ant-Man,” set for release in 2015. Ant-Man is the superhero alter ego of Pym, a scientist who invents a shrinking serum that allows him to sneak around in miniature form and surprise foes — he’s also one of the original members of the Avengers.

Both “Ant-Man” and “Guardians” will launch likely new franchises for the comic book movie giant.

In addition to Diesel, the “Guardians of the Galaxy” cast boasts plenty of stars familiar to fans of genre entertainment, as well as some seemingly unlikely newcomers. Glenn Close (“Fatal Attraction,” “Mars Attacks”) will play Nova-Prime, the highest ranking officer in Marvel Comics’ intergalactic police force Nova Corps. (Though several comic characters have held the Nova-Prime title, all have been men.)